Ground effect machines with supply and recovery ports in a common duct



July 13, 1965 c. s. COCKERELL 3,194,333

GROUND EFFECT MACHINES WITH SUPPLY AND RECOVERY PORTS IN A COMMON DUCT 3 Sheets-Sheet 1 Filed April 5, 1951 Iave afar C. S. Coons-35L A-kB July 13, 1965 c. s. COCKERELL 3,194,333

(mourn) EFFECT MACHINES WITH SUPPLY AND RECOVERY PORTS IN A COMMON DUCT Filed April 5, 1961 3 Sheets-Sheet 2 Ihven/"ar C. S. CacKfiktLL l9 #omexs July 13, 1965 c. s. COCKERELL 3,194,333

GROUND EFFECT MACHINES WITH SUPPLY AND RECOVERY PORTS IN A COMMON DUCT Filed April 5, 1961 5 Sheets-Sheet 5 FIG.

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mh Iv a m I I "m INVENTOR C 5. COCKERELL.

ATTORNEYS United States Patent 0 3,194,333 GROUND EFFECT MACHINES WITH SUPPLY AND RECGVERY PORTS IN A COR [MUN DUCT Christopher Sydney Uoekerell, Lyniington, England, assignor to Hovercraft Development Limited, London, England, a British company Filed Apr. 3, 1961, Ser. No. 100,134 Claims priority, application Great Britain, Apr. 5, 196%,

12,095/60 11 Claims. (Cl. 180-7) This invention relates to vehicles in which provision is made for the ejection of one or more jets of fluid through one or more annular supply ports, or series of supply ports in an annular configuration, in the bottom of the vehicle to form one or more fluid curtains, the ejection of the fluid resulting in the formation of a cushion of pressurised fluid, the said cushion being contained beneath the vehicle, at least in part, by the said fluid curtain, and in which at least part of the fluid forming the said curtain is recovered through at least one recovery port or series of recovery ports in an annular configuration. Such vehicles are described in the specifications of (Io-pending application Serial No. 837,428, filed Sept. 1, 1959.

In vehicles of the type described in the above mentioned specifications the fluid which is ejected through the supply ports is supplied by means of at least one duct, the fluid being fed into the duct by a suitable compressor or the like, The fluid recovered through the recovery ports is again generally fed to at least one further duct, the fluid in this duct being used in various ways such as by recirculating it back to the initial curtain, using it to form a further curtain or for propulsion or other purposes.

The amount of fluid remaining in the duct feeding the supply port, or ports, decreases as the distance from the compressor increases, due to the fluid being ejected through the supply port The required cross sectional area of the duct decreases, therefore, from one end to the other. Conversely, the amount of fluid in the recovery duct increases as more recovered fluid is fed to it and the required cross section increases up to the point of utilisation of the recovered fluid. To use ducts of constant cross sectional area is inefflcient in weight and space. The use of tapering ducts does not always provide the most elhcient and economical method.

The provision of a common duct for the fluid for the supply port or ports and for the recovered fluid such that the decrease in volume due to the ejection of curtain fluid is counterbalanced by the increasing volume of recovered air is a convenient form of installation and according to the invention there is provided a vehicle of the type described in which co-acting supply and recovery ports are formed in a wall of a common duct, and in which there is provided means for causing a flow of energised fluid through the common duct, ejection means in the supply port or ports and induction means in the recovery port or ports whereby when a flow of energised fluid occurs through the duct the ejection means causes at least part of the energised fluid to be discharged through the supply port to form the curtain and the induction means causes at least part of the fluid forming the curtain to be induced through the recovery port into the duct.

Generally the fluid is a gas and for convenience is hereinafter referred to as air, although other gases such as exhaust gases can be used.

Certain embodiments of the invention will now be described by way of example in conjunction with the accompanying drawings in which:

FIGURE 1 is a vertical cross section through the periphery of a vehicle, illustrating one embodiment of the invention,

'ice

FIGURE 2 is a fragmentary cross section on the line A-A of FIGURE 1,

FIGURE 3 is a fragmentary cross section on the line B--B of FIGURE 1,

FIGURE 4 is a cross section similar to FIGURE 1, illustrating an alternative arrangement,

FIGURE 5 is a plan view of a vehicle embodying the invention,

FIGURE 6 is a front elevation of the vehicle illustrated in FIGURE 5,

FIGURE 7 is a side elevation of the vehicle illustrated in FIGURE 5,

FIGURE 8 is a vertical cross section normal the fore and aft axis, of a further form of vehicle embodying the invention,

FIGURES 9, 10, 11 and 12 are cross sections similar to FIGURES 1, 2, 3 and 4, respectively, illustrating modifications of the arrangements shown in the latter figures wherein the vanes are rotatably mounted, and

FIGURE 13 is a cross section similar to FIGURE 1 illustrating another form of the invention.

FIGURES 1-3 illustrate the application of the invention to an air curtain system in which the curtain forming air is recovered through recovery ports situated inboard of the supply ports. A duct 1 is formed round the periphery of the bottom of the vehicle. A supply port 2 and a recovery port 3 are formed in the bottom wall of the duct, the ports being annular or composed of a series of ports in an annular configuration, the recovery port 3 being substantially parallel to and inboard of the supply port 2. Fixed in the supply port 2 are vanes 4 of aerofoil cross section, having one surface 411 convex and the other surface 4b concave. The leading edges 40 of the vanes are level with the inner bottom surface Ia of the duct 1, the concave faces facing against the direction of flow of air through the duct when the vehicle is in operation. The shape and disposition of the vanes is readily seen in FIGURE 2 which is a cross section on the line AA of FIGURE 1. Further vanes 5 of similar cross section are fixed in the recovery port, the vanes having their trailing edges 5a level with the inner bottom surface Icz of the duct 1. Their concave faces 512 face in the same direction as the air flow in the duct, and the shape and disposition of the vanes 5 is shown in FIGURE 3 which is a cross section on the line B-B of FIGURE 1.

In operation air is caused to flow continuously through the duct 1 by one or more compressors or the like. Some of the air is ejected through the vanes 4 in the supply port 2 in the form of a curtain C flowing inwards toward the centre of the bottom B of the vehicle. As a cushion P of pressurised air builds up beneath the vehicle, the vehicle tends to lift, and the curtain of air is deflected, part flowing into the recovery port 3. The recovery of air through the recovery port is enhanced by the induction effect of the air in the duct 1 flowing past the trailing edges 5a of the vanes 5. As the cushion of pressurised air beneath the vehicle builds up it is lifted off the surface S and eventually an equilibrium condition is reached in which the curtain of air from the supply port flows first downwards and inwards until it reaches the surface when it is deflected inwards. The cushion of pressurised air then deflects the curtain round and upwardly towards the bottom surface of the vehicle, the air flowing into the recovery port 3 assisted by the aforementioned induction effect, as can be seen in FIGURES 1 and 3.

The supply port 2 is shown in FIGURE 1 as being directed inwards towards the centre of the vehicle at about 45 with the vertical but this angle may be varied.

In an alternative arrangement, as illustrated in FIG- URE 4, the relative positions of the supply and recovery ports are reversed, the supply port 6 being on the inside and the recovery port 7 on the outside. The air curtain will then have the form shown, flowing first, downwards andinwards and being deflected round andoutwards by the cushion pressure. a

The provision of a common duct provides a convenien system for vehicles: in which the recovered air is used for propulsion. FIGURES 5, 6, 7 and 8 illustrate two forms of such vehicles. r

In the vehicle shown is FIGURES 5, 6, and 7, an is" drawn in through'an intake :10 by a propeller 11. The propeller is driven by a motor12. The air is forced by the propeller into two ducts 13- and 14- positioned one along each side of the vehicle and extending substan: tially the length thereof.- The cross section of the ducts rection. By subdividing the cushion'flspace, thestability of the vehicle is'improved.

The vanes 4 and/or. 5 of FIGURESil to4 and the vanes 25 and/or 26 of FIGURE, 8 :may be mounted: in 17 7 their respective ports so that they are capablef of rotation about'horizontalaxes. 'Forexamplejas shown in 13 and 14 are for example similar to that shown in FIGURE 1. A supply port 15 and a recovery port 16 are formed in the bottom wall of the duct for the supply and'recovery of the air and the arrangement of the vanes in the ports Hand 16 is similar to that shown in FIG; The ductsv 13 and 14 are terminated at URES 2 and 3. their rear ends to form'propulsion" nozzles 17 and the recovered air plus any additional air which flows throughthe ducts is expelled from the nozzles 17 and propels the vehicle: Some of the air entering the ducts 13 and 14 at the front of the vehicle is fed to .a port 18 formed in the vbottom of thevehicle and'extending across the front of the vehicle, to form a curtain. This, curtain may be of a simple form, like the single curtain shown in co-= pending application Serial No. 627,925, filed December 12, 1956, or of the type in which at least part of the curtain-forming air is recovered into the vehicle through a recovery port and then reissues through a supply port so as to either'recirculate in the curtain or form a second curtain, as shown in co-pending application Serial No. 809,699, filed April 29, 1959.

The invention is particularly applicable for vehicles in which side walls extend downwards. on each side of the vehicle, substantially for the length thereof, such 'as are described, and illustrated in the co-pending application Serial No. 819,968, filed June 12, 1959. FIG- URE 8 is a vertical c'ross section normal to the longi tudinal axis of sueh a vehicle. A side wall 21} extends along each side of the vehicle projecting downwards from the'main body '21 of the vehicle. prises a duct 22 through which energised air is caused to flow. Supply ports 23 and recovery ports 24 are formed in the bottom walls of the side walls and vanes 25. and

26 are positioned inthe supply ports 23 and recovery ports 24'respectively, as described above. The flow of energised air through the ducts 22 results in the formation of air curtains 27 as described above and the air is eventually expelled from propulsion nozzles at the rear ends of the ducts 22 in a similar manner as in FIGURE 5. Further an curtains are formed across the back and front of the vehicle by any suitable means, such as thosedisclosed in the abovementioned co-pending application Serial. No. 819,968 and the corresponding Australian Patent No. 232,436., I

The cushion space may be, subdivided by 'further structural members; depending from the bottom surface of the vehicle, as shown at 28 in FIGURE 8,.for example. Alternatively the cushion space may be subdivided by further air curtains formed from additional supply ports in the bottom surface of the vehicle, suchias those shown in the previously mentioned co-pending application Serial No. 627,925 and the corresponding British Patent No. Subdivision by air curtains is preferable, when.- ina direction transverse to the direction of movement:

of the vehicle. I Curtainsof air may, also be formed from the bottom. edges of any depending structural members as disclosed in the above-mentioned co-pending application Serial No. 819,968 and Australian Patent No.

232,436. The member ZS in FIGURE 8 may be pro vided Witha supply port in the bottom edge and a duct leading from the air supply. to the port. curtain will normally issue in a vertically downward di- Each side wall conr:

Such an air* vehicle, 7 .v v 3. A vehicleas'claimed in clairrr l pinwihich ithe duct- 1 extends; along each side of the vehicle andround the,

rear of the vehicle, separatecurtain forming. meafnsbeing FEGURES 9-12, thevanesfi and'fi may be'mounted on 7 horizontal pivots- 30 and rotated about the axesthereof by flexible wires or cables 31 suitably attached :to the vanes at positions offset-from said ax'es. Such rotation 'aets to vary the angle of-incidencerof the vanes relative;

to the air flow through the ducts 1 'ori22;' By this means,

the mass flow of the airi curtains mayjbe varied either, I forthe whole length of the vehicle, or locally: Direca; tional components may also be imposed on the airforming the curtains to provide propulsion, steeringlmoments or the like or combinationsof these;

Multiplecurtain systems -n1ay'-be"= iormed"for apart a or whole of. the: periphery ofthe vehicle" by the 'provisionf of. two or more ducts; substantially parallel to each other" for a part or-the whole of the-periphery Ofthe vehicle,

asshown in'FIGURE 13."

'l claimz: i

tudinal axis, ejection means in' the supply portwhereby when a iiow offluid occurs through the duct'in :adirec tion parallel to said longitudinalaxis atleast part ofthe J fluid is ejected through the s'upply'port to'form aculr: tain, and induction means in'the recovery portiwhereby at least partof 'the fluid .forming thelcu'rtain.is'induced1 through the. recoveryportinto the duct to rejoin thefiuid flowing axially through said duct.

21A vehicle as claimed in claim 15in which the duct, comprises a section formed along each side' of the vehicle: a in the bottom thereof, flow of fluid throughithe said duct.

sections causingthe formation of a" curtain of fluid be-- neath each duct section, 2 separate curtain V forming means being provided atthe .front and rear-of the vehiclefor: closing any gap which foccurs between. the. curtains; formed beneath the duct sectionsalong .the'sides of. the

provided at the frontflo'fzathevehicle.

4..Ave hicle as claimed in claim 2 in whichlthe, due iii sections along thersid'es, of the. vehicle dependtroin the bottom surface ,of'the vehicle; in ,thej form of walls;

5. A vehicle as'clairned-in claim l in which :the duct terminates in a: propulsion nozzle, and at leastup'art. of

t the fluid flowing through the duct is propulsion nozzle; 6. .A vehicle as claimed a positive angle of inciden'ce relative to such'ifiow.

7. A vehicle as'claimedin claim =6 in whichmeans are" provided for varying the angle oftincidence; of the vanes. 81 -A vehicle of the type describedcoriiprising a duct positioned around at least partv of-tthe -peripheryof the bottom of the ;vehic'le',.-the longitudinal axi s;1of=the duct 7 being substantially parallel to theperiphery of .thevehicle, supply and recovery portsgfoi'medhi the vwall of thejduct and. extending along said ductparallelito the longitudinal axis thereoflzmeans for causingfa fiow of energised fluid throughstheduct. in a 'direction parallel' to its longitudinal axis, ejection means in the supply port vwhereby when'a flow of lfluidf'occurs' throughthe duct 5;

ejected through the "in claiinl irilwhich the ejec-. a tion' means' in the supply port'comprises .a series of vanes normal to thefiowof fluid through the ductgand having' in a direction parallel to said longitudinal axis at least part of the fluid is ejected throughvthe supply port to form a curtain, and induction means in the recovery port whereby at least part of the fluid forming the curtain is induced through the recovery port into the duct to rejoin the fluid flowing axially through said duct, said induction means comprising a series of vanes normal to the flow of fluid through the duct, and having a negative angle of incidence relative to such flow.

9. A vehicle as claimed in claim 8 in which means are provided for varying the angle of incidence of the vanes.

10. A vehicle of the type described comprising a duct positioner round at least part of the periphery of the bottom of the vehicle, the longitudinal axis of the duct being substantially parallel to the periphery of the vehicle, supply and recovery ports formed in the wall of the duct and extending along said duct parallel to the longitudinal axis thereof, means for causing a flow of energised fluid through the duct in a direction parallel to its longitudinal axis, ejection means in the supply port comprising a first series of vanes normal to the flow of fluid through the duct, and having a positive angle of incidence relative to such flow, whereby when a flow of fluid occurs through the duct in a direction parallel to said longitudinal axis at least part of the fluid is ejected through the supply port 2 to form a curtain, and induction means in the recovery port comprising a second series of vanes normal to the how of fluid through the duct, and having a negative angle of incidence relative to such flow, whereby at least part of the fluid forming the curtain is induced through the recovery port into the duct to rejoin the fluid flowing axially through said duct.

11. A vehicle as claimed in claim 10 including means for varying the angles of incidence of said first and second series of vanes.

References Cited by the Examiner UNITED STATES PATENTS 2,322,790 6/43 Cristadoro. 2,838,257 6/58 Wi'oault.

FOREIGN PATENTS 219,133 11/58 Australia.

OTHER REFERENCES SAE Journal, March 1960, pages 26-29.

Science and Mechanics, June 1960, pages 73-77.

Symposium on Ground Effect Phenomena, Oct. 21- 23, 1959, pages 132 and 328 relied on.

A. HARRY LEVY, Primary Examiner.

PHILIP ARNOLD, Examiner. 

1. A VEHICLE OF THE TYPE DESCRIBED COMPRISING A DUCT POSITIONED ROUND AT LEAST PART OF THE PERIPHERY OF THE BOTTOM OF THE VEHICLE, THE LONGITUDINAL AXIS OF THE DUCT BEING SUBSTANTIALLY PARALLEL TO THE PERIPHERY OF THE VEHICLE, SUPPLY AND RECOVERY PORTS FORMED IN THE WALL OF THE DUCT AND EXTENDING ALONG SAID DUCT PARALLEL TO THE LONGITUDINAL AXIS THEREOF, MEANS FOR CAUSING A FLOW OF ENERGISED FLUID THROUGH THE DUCT IN A DIRECTION PARALLEL TO ITS LONGITUDINAL AXIS, EJECTION MEANS IN THE SUPPLY PORT WHEREBY WHEN A FLOW OF FLUID OCCURS THROUGH THE DUCT IN A DIRECTION PARALLEL TO SAID LONGITUDINAL AXIS AT LEAST PART OF THE FLUID IS EJECTED THROUGH THE SUPPLY PORT TO FORM A CURTAIN, AND INDUCTION MEANS IN THE RECOVERY PORT WHEREBY AT LEAST PART OF THE FLUID FORMING THE CURTAIN IS INDUCED THROUGH THE RECOVERY PORT INTO THE DUCT TO REJOIN THE FLUID FLOWING AXIALLY THROUGH SAID DUCT. 